Editor's note: Dr. Charles Raison, CNNhealth's mental health expert, is an associate professor of psychiatry at the University of Arizona in Tucson.

Ever noticed how scientific opinions swing from one extreme to the other?

Take the importance of mothers in the development of children. In the early days of psychiatry almost every mental illness, from depression to schizophrenia to autism was blamed on bad mothering. Then in the 1960’s and 70’s the discovery of medications that helped these illnesses allowed psychiatry to reframe them as biological conditions, no different from cancer or heart disease. Parents were fully absolved for the mental illnesses of their children, except to the degree that they passed along bad genes that caused chemical imbalances in the brain.

Myths inevitably survive long after they’ve been scientifically disproven. Such is the case with the fantasy that mental illnesses can be written off solely to genes and chemicals. Over the last decade a string of scientific discoveries has shown that the biology driving mental illness has at least as much to do with the environment as with chemicals or genetic inheritance. And it increasingly appears that the single most powerful environmental factor is the love - or its lack - that children receive from their parents. So in a very real way we parents are back on the hook for the lifelong emotional well-being of our kids.

Here’s how the study was done. Researchers at Washington University in St. Louis recruited 92 children between the ages of 3 and 6. Rather than asking parents about how they treated their children, the researchers brought the kids and parents into a lab and videotaped them as the parents, almost always mothers, tried to help their children cope with a mildly stressful task that was designed to approximate the stress of daily parenting.

Ratings of parental ability to nurture their children were done by study personnel who watched the videos while knowing nothing about either children or parents. Several years later, on average, the children had the size of a brain area called the hippocampus measured using magnetic resonance imaging (MRI). After taking into account a whole range of factors that can affect hippocampal size, the researchers found that children with especially nurturing, caring mothers, based on their behavior during the laboratory stressor, had significantly larger hippocampi (plural of hippocampus - you’ve got one on each side of the brain) than kids with mothers who were average or poor nurturers.

Why is this finding important? Because more than any place else in the brain, when it comes to the hippocampus, size matters. Other things being equal, having small hippocampi increases your risk for all sorts of troubles, from depression and post traumatic stress disorder to Alzheimer’s disease. If you’ve got depression, having small hippocampi predicts that you won’t respond as well to antidepressants as well as depressed people with larger hippocampi.

Just as having small hippocampi increases the risk for all sorts of mental disorders, all the things in our lives that put us under undue stress and strain also shrink the hippocampus. This is as true for cigarette smoking as it is for being exposed as a child to abuse or parental neglect.

In addition to protecting us against brain illnesses, we all need big hippocampi because this brain area, while not much bigger than your little finger, plays a disproportionately large role in how you will be able to handle the stresses and strains of your life, and how you will remember your life when it’s all said and done. This is so because the hippocampus is crucial for our ability to form and store personal memories. It is also of central importance for restraining the body’s stress and inflammatory responses, both of which can induce significant damage to bodily organs and the brain if not properly reined in.

The finding that especially nurturing mothers can literally grow their children’s hippocampi doesn’t exist in isolation. It is consistent with hundreds of animal studies showing that maternal nurturing has a range of biological effects relevant to physical and emotional health. An especially striking example of this is a study done several years ago in rodents showing that maternal nurturance (measured as amount of licking that rat pups received from their mothers) literally changed how the rat pups’ DNA was expressed in the hippocampus. As a result of these changes, pups who received extra licking had changes in their stress systems that have been repeatedly associated with well-being in humans.

So we underestimate our power as parents at our children’s peril. But I would be remiss if I left you with the impression that mother love is all-powerful or that genes and chemicals don’t matter at all. The association of parental nurturing with subsequent hippocampal size in children was only observed in non-depressed children. In children with signs of significant early depression, maternal nurturing in the laboratory had no association with subsequent hippocampal volume. Why this was the case is anybody’s guess, but it might suggest that at least some cases of major depression are indeed mostly genetic or “hardwired” from an early age, and so are fairly resistant to positive things from the environment.

Given the complexity of the human brain, should we be surprised that every possible outcome of genes, chemicals and environment is actualized in someone somewhere? Meantime, one generation full of deeply loving parents would change the brain of the next generation, and with that, the world.

Was thinking of something similar today. We get lots of wild cats out here on the edge of town and if they are young kittens and are handled, they will be socialized domesticated kitties as they grow up, wanting closeness and affection, OK, some when ever They are interested. But if the kittens come around and they have managed to live without a mother or a protector, you will not win them over to touch and domestication. The closest they will ever get is a few feet away. I am convinced the first three years are critical in child development even though I have only been one but never had any....Humm.

My first child is on the way (a little girl) and I plan to love her beyond words and be the best dad I can possibly be. I look at most of the things my dad did to me when I was a kid and I use that as a template for what NOT to be when it comes to being a dad. I see so MANY examples of bad parenting where I live it's ridiculous. 7 year old boys with mohawks and designs shaved into the side of their hair. I mean what kind of parent allows something like that on a 7 year old? So much FAIL parenting out there.

You are actually going to fail at parenting if you think that letting your child do something silly like wear a certain hairstyle is any indicator of quality of parenting. It is an indicator, however, of being the kind of parent that is too pre-occupied about what perceptions others have of you, which actually leads to bad parenting. Sorry and get over yourself.

My 8 year old gets a mohawk every summer and has his baseball team's logo shaved on the side. He plays 3 sports, gets straight 8s and is known by teachers as a kind person who always sticks up for others and never allows bullying in his presence (3 different teachers have told me this). Maybe your dad taught you to be judgmental or maybe its just biology but either way its pretty sad. Basing your entire assumptions about a person based on their hair is pathetic.

Oh please. If your idea of good parenting revolves around controlling your child's attire and judging other parents for not doing the same, then you REALLY have a lot to learn about what a good parent is.

So people are bad parents if you don't agree with the child's hair cut?
How about teaching your child to be there own person and love everyone no matter what they look like?
are we also bad parents if we let our kids pick out there own clothes and wear pink pants with a lime green shirt?
If you try to control every aspect of your childs life they will be more likely to rebel as a teenager. seen it happen allot.

Kudos to you for striving to be a good dad! However, I find your comment regarding 7 yr olds with mo-hawks and designs shaved into the side of their hair as an example of FAIL parenting, particularly misinformed and bothersome. I am a mother of 3 children (8, 4 and 20 months respectively) and my only son (the baby) has a little baby mo-hawk. By your comment, you are judging the caliber of parent I am solely on a hair-do. Can you honestly admit that makes any sense, at all?? I should let you know that the reason I stumbled upon this article is bc my son had brain surgery when he was 3 months old due to a large arachnoid cyst on his brain that needed to be shunted. He now has a large c-shaped scar above his ear where the shunt valve is. He sports a mo-hawk in part, to take attention away from his scar but also bc frankly, in my opinion, I think it's cute. I'd imagine if he hadn't had the surgery, I would still fashion his hair that way. Afterall, it is only hair. Did I mention that he also has epilepsy now, as a result of a lesion on his brain (left temporal lobe) from the pressure of the cyst before it was shunted. As a result, I tirelessly research the brain to make sure he's getting the best care I can (and my husband, his dad) can give him aside from his neurosurgeon and neurologist and other therapists (language, ot, play and music). He is now starting to display some behavioral problems (likely related to the meds he is on to control his epilepsy and to the brain damage he has sustained from the cyst. I wonder what your perception would be of him, and, me, consequently if we were at a park and he threw a temper tantrum- and since he's not verbal (though he can sign some) and he gets frustrated bc he cannot communicate adequately to get his point of view across, so he acts out- I wonder if you would assume, I'm just a negligible parent. I caution you to think before you type as you are not a parent yet and have not been subjected to others' ignorance, intolerance and judgements. When your beautiful daughter-to-be makes her grand debut, I hope she is welcomed and honored into a society where others aren't as close-minded as her father.

While a hairstyle alone can't be a basis for parental judgement, it is a factor in how your child will be treated and perceived by others. We, as human beings, DO judge a book by it's cover. What we wear – clothing, makeup, hairstyles, shoes – tells a lot about us. Grownups make these choices with purpose, supposedly understanding which "category" of people we want to be associated with by our choices. Young children are not aware of the associations we make. The adults who dress them make those choices for them. The children have teachers, school staff, other parents, society in general, who will be making human judgements based on the "covers" that their parents have chosen for them. These choices of hair and clothing DO determine whether others will trust the child, believe them to be dependable, responsible, moral, etc., or if your child will be believed to be a troublemaker, dishonest, immoral, etc. The choices we make as parents, and the choices we allow as our children get older, should be with thought about how the child's life may or may not be affected.

I set my rules for my girls not to have nail polish until they are 10 years old and make up until they are 17. It is working so far, my 8 year old tells me that she will be very happy the day she will use nail polish. But we have to pick the battles, I let her dress what she wants, even though sometimes it looks weird, I can't stop her on everything, we negotiate. So far is working. When puberty hits, will be different story for sure... I'll keep you posted :)

Wow what a bunch of junk science. So now we are supposed to believe that inmates and depressed people weren't loved enough by mommy and that's what causes their problems? How about we look at the zillions of people through time who weren't loved by their mommy either and became great people – or are you just going to look at the bad/depressed people? What freebie grant paid for this cr*p science?

I think you only read the headline. The author notes that the single most important environmental factor to parenting is love, but there are numerous other environmental factors (and biological ones) that have profound effects. Yes, it's possible not to be loved and to grow up to be a well-adjusted adult (read "A Child Called It" by Dave Pelzer for a chilling real-life example), but you're starting out with the deck stacked against you.

Cause and effect fail! Exceptions don't disprove the rule. Correlations don't have to be 100%, they just have to be non zero. And no, this wasn't a sneaky attempt to make you have compassion for the minorities in jail. All is well in your world. Go back to bed.

Hi there! I know this is somewhat off-topic but I had to ask. Does mainnagg a well-established blog like yours require a massive amount work? I am brand new to running a blog but I do write in my diary daily. I'd like to start a blog so I will be able to share my own experience and feelings online. Please let me know if you have any kind of ideas or tips for new aspiring bloggers. Appreciate it!

The author speaks of "parents" but notes, in passing, that the subjects of the study were "almost always mothers". So where does that leave fathers? The word "father" doesn't even appear in the article. A lot of us fathers try to do the best for our children, so it would be interesting to hear more about our role as well.

In the field of research, it is very difficult to recruit enough fathers willing/able to participate in study. One researcher in particular at Ohio State is focusing her research on the father's impact. It can be done but with funding so tight, the funders want good results and numbers of participants matter.

what I do like about this article is that it is stating that "nuturing" is important. I feel like as a society we have been downplaying, dismissing, and outright sabatoging the great importance of maternal nurturing. Nuturing should be held in the highest regard, it should be repected and celebrated. It is important! It is powerful. A father's love and nurturing is equally important. We need loving fathers! They are the ying to our yang! There can't ever be enough nurturing. Nurture yourself, nurture one another, nurture your children – marinate your family in love. Who knows, if everyone did this we may have nurturing/loving neighborhoods, cities, schools and perhaps a nuturing government as well. A government that is in balance that spends as much of it's budget on healthcare and education(nuturing) as it does on military(protecting) because each are equally important.

I think this is BS. My parents used to abuse the heck out of us as kids mentally and physically, and I am completely fine psychologically, and am also successful career and relationship wise. Life is what you choose to make of it.

The article did not say lack of love makes EVERYONE mentally unstable. The chances are much higher for mental instability when a child is raised in a home where there is LACK of love; and lack of love doesn't necessarily mean the child's life was completely void of love; it could also mean love was lacking when it was needed most in the child's life.

I can agree that love is important, but the article states: "Ihippocampi ...plays a disproportionately large role in how you will be able to handle the stresses and strains of your life" Wouldn't it be safe to assume that the more nurturing mothers had larger hippocampi and thus were able to handle the stress of mothering easier and then pass that genetic trait of a larger hippocampus to their children? Were the mother's hippocampi even measured? In another study of twins raised apart, it is found that there is very little difference in IQ or personal characteristics even if they were raised differently, suggesting that genetics actually plays a larger role. Don't get me wrong, I hope this inspires people to be loving parents but I'm not sure I agree with the research method.

The authors address this issue on p. 2857-2858: "On the basis of these data, one cannot
rule out that the relationship between maternal support and
hippocampal volume in offspring is based on genetic factors, that
supportive caregivers could have larger hippocampal volumes
and then have biological children with larger volumes. However,
there is no evidence in the literature of a relationship between
hippocampal volume and supportive care giving in adults."

Bad parents are the worst, both of mine were nightmares and I have spent my entire life playing catch-up because when kids start out in a bad home, they start out very far behind, and sometimes can't ever bridge that gap. I think it scares most people to admit that it's really all up to chance, regarding who you get as parents and how things turn out because of that one factor. People like to pretend that they control their own destiny as it's much more comfortable to believe that.

I agreed. My parents were not abusive, but they were never affectionate. They provided the basics...food and shelter..that's all. I never had birthday parties, no toys, clothes were always hand me downs, I was never praised, had no help with homework, I was also molested as a kid and kept it to myself – didn't have anyone to turn to....I became depressed and still struggled with depression.

I have two wonderful children now and I never stop showing them love and support. I know what NOT to do to my children from my experiences with my parents. I was deprived as a child, but I will not let this happen to my kids.

I was raised by a woman (my mother) who hated me. She told me everyday, "you're a child not even a mother can love." Never once did she hold me or love me. No one can mess you up like a mother. PLEASE if you or someone you know has a child she does not want, give the kid away. I wish everyday my mother aborted me or just gave me away.

I know, it's a myth that all parents love their children, they don't. Neither one of my parents ever cared about me and one was extremely abusive. Although I don't suffer from depression and one of my strengths is how I handle stress, it is difficult to struggle with the damage that has been done to me. The rejection of why they didn't love us is probably the hardest. As successful as I am in other areas of my life, I don't think I will ever get over that.

I hear you Isadore. I also had an unaffectionate mother who from the age of 8 on just told me how bad I was. The one thing my mother taught me, however, is never to blame someone else for your shortcomings. I spent most of my life trying to overcome my shortcomings, including depression, anxiety, various fears. Got married, (got divorced) raised a child, worked unhappily in what some might call a successful career. Then one day I realized I'd always felt I was a bad person, and all my problems were all my fault. And it started out at home. Parents can do such damage. I'm still depressed and I'm still anxious, and whenever I see my own shortcomings, I struggle between wanting desperately to fix myself, and telling myself that I really am okay, despite my faults.

Youre so cool! I dont suppose Ive read smitehong like this before. So good to find somebody with some original thoughts on this subject. realy thank you for beginning this up. this website is one thing that's wanted on the internet, someone with just a little originality. useful job for bringing smitehong new to the internet!

This is exactly whyHands to Hearts International (www.handstohearts.org) exists! HHI works in developing countries to train caregivers how to provide improved care for infants and children including how to provide a more loving, nurturing environment as well as ways to improve early childhood development. Mother, fathers, caregivers of all sorts can change their baby's life with simple interventions like these.

Interesting, because I do think my mother loved me (father couldn't have cared less but wasn't mean), but she was bipolar and I was beaten up by my brother as a child. Thing is, good grades were what gave me an escape and I got into two Ivies and went to the better one.

I think there is a HUGE gap between "LOVE" and "nurturing" and "caring" and "abuse". Most people do okay as long as they aren't actually abused (and as I mentioned, I was abused but not by my parents). I suppose the idea of someone "in your corner" is helpful to all.

In the real world, what defines a mother or father's love. For every parent out there you will get a slightly different answer. Is nurturing buying the newest toy or keeping them warm and secure at night? Many parents who love their kids whack them when they misbehave. Others find this practice abhorrent. Is listening to their minor social problems showing love. Or, in the case of a boy, who was picked
on telling him to grow up and be a man
nurturing? Studies like this may be helpful in a perfect clinical setting, but fall apart in the real world!

I lived with horrible, abusive parents as a child, but was really raised by a horrible, abusive psychiatric system. I imagine between what I endured at home and all the neuroleptics I was force fed as a child, I probably don't even have a hippocampus. And my parents were constantly extolled as "blameless" for my "illness." On one memorable occasion my father was praised by a therapist for beating me and throwing me down the stairs to force me to come to an appointment. I can honestly say I hate the system more than I hate them. Articles like this make me angry – it's like they're trying to stop a runaway truck with a gentle nudge.

So sorry you experienced that Stacey. I can truly relate to what you say about all the pyschobabbling out there. Sometimes that can be more harmful than what it is originally intended for. We all might benefit from thinking for ourselves instead of constantly worrying about the opinions of these people with letters after their names. They may be contributing to a nation of self-centered, child-obsessed, paranoid parents at best, and at worst, what you have gone through.
Regardless, I'm sorry for your pain. And it appears you most likely have a sizable hippocampus, regardless of the article.

The most destructive force in any society is selfishness and pride. Selfishness makes men beat and abuse their wives. It makes wives humiliate, shame and belittle their husbands. Why are some women so callous toward their children? Why are some men so emotionally insensitive? You can almost always find the answer in their own experience of an empty, loveless childhood, but instead of sympathy, marriage mates / romantic partners just think about themselves and how their partners are failing to meet their expectations and turn to abusive, coercive measures in an effort to 'straighten them out'. The end result is a failed relationship that just further empties out both partners and keeps them supremely unfit to meet the emotional needs of their children.

My heart goes out to all of the commenters that have experienced such trauma from their parents. I'm so sorry that your families let you down. I hope you are able to find some peace by knowing that your parents are the bad people...not you.

My partner's and my situation seems to be the opposite– he was coddled and encouraged as a kid, while my mom had paranoid schizophrenia (and didn't take her meds for years) and couldn't care for me properly. Now he's the one with mental illness and I'm (relatively) normal.

My wife's first reaction to the dramatic increase in Autism was bad parenting. More specifically her concern is that mothers are less engaged with their children due to texting, cell phones, computers, video game and career obligations so children receive much less touching, parental and social interaction. Has anyone studied these correlations?

I know several children with autism, and none of them were raised the way you're describing. I do know lots of children who were raised by parents who were quite disengaged and wrapped up with their gadgets and, in some cases, careers. One of them happens to have autism, but only one.

I'm in my 40s, and I knew lots of disengaged parents, even before cellphones, texting and videogames. There are hundreds, if not thousands, of ways for a parent (or spouse, for that matter) to disengage from their children. They're just not all as easy to see and point to as technology.

I wonder if there is any study in other countries like Sweden or Norway or France where there is way more support for families with kids. What is the percentage of abused kids in these countries? I wonder.

It is heartbreaking to hear of the damage parents can cause! Last fall I took a life-changing weekend course called Parentology tm. Even though my boys are 21 & 18, and are happy and success, I learned that I can do so much better as a parent. It is the best investment you can make for your family.

I would just like to say, I came from a terribly abusive childhood. My parents were more into themselves, and drugs, than me. My father's depression finally ended his life. My Mother grew far more abusive, until I finally turned 18 and was free to leave that mess. However, the lack of love and nurturing in my childhood was the basis I used to do exactly the opposite of my parents for my own children. You can survive all kinds of abuse and still function well as a very loving and nurturing parent yourself!

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"children with signs of significant early depression, maternal nurturing in the laboratory had no association with subsequent hippocampal volume"

I was wondering if this might have something to do with the mother's mental/physical health and diet during pregnancy. For instance, if we now know that babies born to obese women have a different fat structure than babies born to normal weight women and have lower IQ's, then might that also be a factor in the development of the hippocampus? Also, could stress during pregnancy factor in there as well?

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